Help w/ HP 88780 Tape Drive (corrected email).

Ethan Dicks ethan.dicks at
Thu Dec 3 12:27:04 CST 2015

On Thu, Dec 3, 2015 at 1:05 PM, Ali <cctalk at> wrote:
> So I got my hands on an HP 88780 1/2" Tape Drive...
> The bad news:
> Some of the front panel buttons are not working. Running test 72 shows
> failure in the unload/rewind and online buttons. Luckily it seems to be a
> mechanical problem. If I short the switch on the circuit board then the test
> passes. The switches are mechanical push buttons that are soldered on so
> should be easy to replace. Anyone know of a good or OEM equivalent
> replacement? If need be I can get pictures of the buttons off the PCB.

I have been recently cleaning and testing an HP 7980A.  I also had
problems with some of the mechanical buttons, verified with TEST 72.
I was able to clean most of them with contact cleaner and agitation,
but the ONLINE button was stubborn.  I ended up replacing it with a
generic 2-pin tactile switch.  I do not know where to get OEM switches
of this exact type - they are somewhat taller than cheap tactile
switches, and appear to have a solid conductive rubber button/pad
instead of a plastic top and metal internals.  My defective button has
a closed resistance measuring in multiple K ohms.

I would also love to hear of a source of replacement buttons of the
original style.


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